Auto merge of rust-lang#74194 - mbrubeck:slice-eq, r=sfackler

Add PartialEq impls for Vec <-> slice

This is a follow-up to rust-lang#71660 and rust-lang/rfcs#2917 to add two more missing vec/slice PartialEq impls:

```
impl<A, B> PartialEq<[B]> for Vec<A> where A: PartialEq<B> { .. }
impl<A, B> PartialEq<Vec<B>> for [A] where A: PartialEq<B> { .. }
```

Since this is insta-stable, it should go through the `@rust-lang/libs` FCP process.  Note that I used version 1.47.0 for the `stable` attribute because I assume this will not merge before the 1.46.0 branch is cut next week.

Author: bors

library/alloc/src/vec.rs

@@ -2591,6 +2591,8 @@ __impl_slice_eq1! { [] Vec<A>, &[B], #[stable(feature = "rust1", since = "1.0.0"
 __impl_slice_eq1! { [] Vec<A>, &mut [B], #[stable(feature = "rust1", since = "1.0.0")] }
 __impl_slice_eq1! { [] &[A], Vec<B>, #[stable(feature = "partialeq_vec_for_ref_slice", since = "1.46.0")] }
 __impl_slice_eq1! { [] &mut [A], Vec<B>, #[stable(feature = "partialeq_vec_for_ref_slice", since = "1.46.0")] }
+__impl_slice_eq1! { [] Vec<A>, [B], #[stable(feature = "partialeq_vec_for_slice", since = "1.48.0")]  }
+__impl_slice_eq1! { [] [A], Vec<B>, #[stable(feature = "partialeq_vec_for_slice", since = "1.48.0")]  }
 __impl_slice_eq1! { [] Cow<'_, [A]>, Vec<B> where A: Clone, #[stable(feature = "rust1", since = "1.0.0")] }
 __impl_slice_eq1! { [] Cow<'_, [A]>, &[B] where A: Clone, #[stable(feature = "rust1", since = "1.0.0")] }
 __impl_slice_eq1! { [] Cow<'_, [A]>, &mut [B] where A: Clone, #[stable(feature = "rust1", since = "1.0.0")] }

library/alloc/tests/vec.rs

@@ -1799,7 +1799,7 @@ fn partialeq_vec_and_prim() {
 }
 
 macro_rules! assert_partial_eq_valid {
-    ($a2:ident, $a3:ident; $b2:ident, $b3: ident) => {
+    ($a2:expr, $a3:expr; $b2:expr, $b3: expr) => {
         assert!($a2 == $b2);
         assert!($a2 != $b3);
         assert!($a3 != $b2);
@@ -1831,6 +1831,7 @@ fn partialeq_vec_full() {
     assert_partial_eq_valid!(slicemut2,slicemut3; vec2,vec3);
     assert_partial_eq_valid!(vec2,vec3; array2,array3);
     assert_partial_eq_valid!(vec2,vec3; arrayref2,arrayref3);
+    assert_partial_eq_valid!(vec2,vec3; arrayref2[..],arrayref3[..]);
 }
 
 #[test]